Phys. Rev. Lett.
97,
262002
(2006)
[5 pages]
Scaling Tests of the Cross Section for Deeply Virtual Compton Scattering
C. Muñoz Camacho et al. Jefferson Lab Hall A Collaboration
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C. Muñoz Camacho1, A. Camsonne2, M. Mazouz3, C. Ferdi2, G. Gavalian4, E. Kuchina5, M. Amarian4, K. A. Aniol6, M. Beaumel1, H. Benaoum7, P. Bertin2,8, M. Brossard2, J.-P. Chen8, E. Chudakov8, B. Craver9, F. Cusanno10, C. W. de Jager8, A. Deur8, R. Feuerbach8, J.-M. Fieschi2, S. Frullani10, M. Garçon1, F. Garibaldi10, O. Gayou11, R. Gilman5, J. Gomez8, P. Gueye12, P. A. M. Guichon1, B. Guillon3, O. Hansen8, D. Hayes4, D. Higinbotham8, T. Holmstrom13, C. E. Hyde-Wright4, H. Ibrahim4, R. Igarashi14, X. Jiang5, H. S. Jo15, L. J. Kaufman16, A. Kelleher13, A. Kolarkar17, G. Kumbartzki5, G. Laveissière2, J. J. LeRose8, R. Lindgren9, N. Liyanage9, H.-J. Lu18, D. J. Margaziotis6, Z.-E. Meziani19, K. McCormick5, R. Michaels8, B. Michel2, B. Moffit13, P. Monaghan11, S. Nanda8, V. Nelyubin9, M. Potokar20, Y. Qiang11, R. D. Ransome5, J.-S. Réal3, B. Reitz8, Y. Roblin8, J. Roche8, F. Sabatié1, A. Saha8, S. Sirca20, K. Slifer9, P. Solvignon19, R. Subedi21, V. Sulkosky13, P. E. Ulmer4, E. Voutier3, K. Wang9, L. B. Weinstein4, B. Wojtsekhowski8, X. Zheng22, and L. Zhu23 (Jefferson Lab Hall A Collaboration)
1CEA Saclay, DAPNIA/SPhN, F-91191 Gif-sur-Yvette, France
2Université Blaise Pascal/CNRS-IN2P3, F-63177 Aubière, France
3Laboratoire de Physique Subatomique et de Cosmologie, 38026 Grenoble, France
4Old Dominion University, Norfolk, Virginia 23508, USA
5Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA
6California State University, Los Angeles, Los Angeles, California 90032, USA
7Syracuse University, Syracuse, New York 13244, USA
8Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
9University of Virginia, Charlottesville, Virginia 22904, USA
10INFN/Sezione Sanità, 00161 Roma, Italy
11Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
12Hampton University, Hampton, Virginia 23668, USA
13College of William and Mary, Williamsburg, Virginia 23187, USA
14University of Saskatchewan, Saskatchewan, Saskatchewan, Canada, S7N 5C6
15Institut de Physique Nucléaire CNRS-IN2P3, Orsay, France
16University of Massachusetts Amherst, Amherst, Massachusetts 01003, USA
17University of Kentucky, Lexington, Kentucky 40506, USA
18Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
19Temple University, Philadelphia, Pennsylvania 19122, USA
20Institut Jozef Stefan, University of Ljubljana, Ljubljana, Slovenia
21Kent State University, Kent, Ohio 44242, USA
22Argonne National Laboratory, Argonne, Illinois, 60439, USA
23University of Illinois, Urbana, Illinois 61801, USA
Received 26 July 2006; published 29 December 2006
We present the first measurements of the e⃗p→epγ cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region. The Q2 dependence (from 1.5 to 2.3 GeV2) of the helicity-dependent cross section indicates the twist-2 dominance of DVCS, proving that generalized parton distributions (GPDs) are accessible to experiment at moderate Q2. The helicity-independent cross section is also measured at Q2=2.3 GeV2. We present the first model-independent measurement of linear combinations of GPDs and GPD integrals up to the twist-3 approximation.
© 2006 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.97.262002
DOI:
10.1103/PhysRevLett.97.262002
PACS:
13.60.Fz, 13.40.Gp, 13.60.Hb, 14.20.Dh
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